Faucet including a capacitance based sensor

ABSTRACT

An electronic faucet is provided that includes a spout having a passageway configured to conduct fluid flow through the spout, an electrically operable valve coupled to the passageway, and a capacitive sensor coupled to the faucet. A controller may dynamically change on/off thresholds and monitor a stability signal to determine when to turn off the electrically operable valve.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 61/381,045, filed Sep. 8, 2010, entitled “FAUCETINCLUDING A CAPACITANCE BASED SENSOR,” the disclosure of which isexpressly incorporated by reference herein.

BACKGROUND AND SUMMARY

The present disclosure relates generally to electronic faucets. Moreparticularly, the present disclosure relates to capacitive sensingsystems and methods for operating a faucet.

Electronic faucets are often used to control fluid flow. Some electronicfaucets include proximity sensors such as active infrared (“IR”)proximity detectors or capacitive proximity sensors to control operationof the faucet. Such proximity sensors are used to detect a user's handspositioned near the faucet and to automatically start fluid flow throughthe faucet in response to detection of the user's hands. Otherelectronic faucets use touch sensors to control the faucet. Such touchsensors may include capacitive touch sensors or other types of touchsensors located on a spout or on a handle of the faucet for controllingoperation of the faucet. Electronic faucets may also include separatetouch and proximity sensors.

The present disclosure relates to a faucet including a capacitance basedsensor. Capacitance by nature changes due to environmental factors ofthe faucet system, including installation, water conductivity, and age.For example, capacitance readings may change based upon the location ofconductive items (such as soap dishes, cleaning utensils, toiletryitems, and cooking items, for example) near the faucet and/or deposits(such as minerals or soap scum, for example) on the faucet itself. Thechanges in capacitance due to environmental factors may causeoperational problems, such as causing the faucet to not turn on, to stayon, or to oscillate between off and on, for example.

In one embodiment, the system of the present disclosure is configured toprovide consistent and reliable on/off control of the faucet throughoutthe life of the product.

According to an illustrative embodiment of the present disclosure, thesystem includes a controller configured to dynamically change the on/offthresholds of the faucet to account for capacitance changes due toenvironmental factors and to monitor signal stability to determine whento turn on and when to turn off the faucet.

According to another illustrative embodiment of the present disclosure,the system deviates from the conventional method of on/off control. Aconventional method may include fixed thresholds, one threshold forturning the faucet off and another threshold for turning the faucet on.An illustrative system of the present disclosure changes thesethresholds dynamically and uses the stability of the signal to determinewhen to turn off the faucet.

According to an illustrative embodiment of the present disclosure, anelectronic faucet is provided comprising a spout having a passagewayconfigured to deliver fluid through the spout. The faucet furtherincludes an electrically operable valve positioned in the passageway anda capacitive sensor coupled to the faucet. A controller is in electricalcommunication with the capacitive sensor and defines a threshold. Thecapacitive sensor is configured to send a signal to the controller. Thecontroller is configured to open the valve when a measure of the signalreaches the threshold and to adjust the threshold in response to atleast one environmental factor.

According to another illustrative embodiment of the present disclosure,an electronic faucet is provided comprising a spout having a passagewayconfigured to deliver fluid through the spout. The faucet furtherincludes an electrically operable valve positioned in the passageway anda capacitive sensor coupled to the faucet and defining a detection area.A controller is in electrical communication with the capacitive sensor.The controller is configured to maintain the valve in an open positionwhen an object is moving within the detection area.

According to yet another illustrative embodiment of the presentdisclosure, a method of controlling an electronic faucet is provided.The method includes the step of providing a faucet including a spouthaving a passageway configured to deliver fluid through the spout. Avalve is positioned in the passageway, and a capacitive sensor iscoupled to the faucet. The method includes the steps of detecting asignal provided with the capacitive sensor and comparing a measure ofthe signal with a threshold. The method further includes the steps ofopening the valve when the measure of the signal reaches the threshold,and adjusting the threshold in response to at least one environmentalfactor.

According to still another illustrative embodiment of the presentdisclosure, a method of controlling an electronic faucet is provided.The method includes the step of providing a faucet including a spouthaving a passageway configured to deliver fluid through the spout. Avalve is positioned in the passageway, and a sensor is coupled to thefaucet. The sensor defines a detection area. The method includes thesteps of positioning the valve in an open position and detectingmovement of an object in the detection area based on a signal providedwith the sensor. The method further includes the step of maintaining thevalve in the open position when the movement of the object is detectedin the detection area.

Additional features and advantages of the present invention will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the illustrative embodiment exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings particularly refers to theaccompanying figures in which:

FIG. 1 is a block diagram illustrating an exemplary electronic faucetincluding a capacitive sensor;

FIG. 2 is a flowchart illustrating an exemplary operation of acapacitive sensing system and method;

FIGS. 3A, 3B, and 3C are flowcharts illustrating the detailed operationof the capacitive sensing system and method of FIG. 2; and

FIG. 4 is a graph of an exemplary output signal of the capacitive sensorof FIG. 1 illustrating changes in the output signal upon the detectionof an object moving in a detection zone of the capacitive sensor.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, which are described herein. The embodimentsdisclosed herein are not intended to be exhaustive or to limit theinvention to the precise form disclosed. Rather, the embodiments arechosen and described so that others skilled in the art may utilize theirteachings. Therefore, no limitation of the scope of the claimedinvention is thereby intended. The present invention includes anyalterations and further modifications of the illustrated devices anddescribed methods and further applications of the principles of theinvention which would normally occur to one skilled in the art to whichthe invention relates.

Referring to FIG. 1, a block diagram of an electronic faucet system 10is illustrated according to one embodiment of the present disclosure.The electronic faucet system 10 includes a spout 12 having a passagewayfor delivering fluids such as water, for example, and at least onemanual valve handle 14 for controlling the flow of fluid through thepassageway of spout 12. A valve body assembly 20 is positioned in thepassageway of spout 12 and is coupled to a hot water source 16 and acold water source 18. In the illustrated embodiment, the passageway ofspout 12 includes all fluid passages between the hot and cold watersources 16, 18 and the output of spout 12. Manual valve handle 14manipulates valve body assembly 20 to control the flow of fluid from thehot and cold water sources 16, 18 through valve body assembly 20. In oneillustrated embodiment, a separate manual valve handle 14 is providedfor each of the hot and cold water sources 16, 18. In other embodiments,such as a faucet system 10 for a kitchen, for example, a single manualvalve handle 14 is used for both hot and cold water delivery. In onekitchen embodiment, manual valve handle 14 and spout 12 are coupled to abasin through a single hole mount.

As illustrated in FIG. 1, an output of valve body assembly 20 is coupledto an actuator driven valve 22 which is controlled electronically byinput signals provided by a controller 24. As such, manual valve handle14 controls the fluid flowing from the hot and cold water sources 16, 18to the input of actuator driven valve 22, and controller 24 controls thefluid flowing from the input of actuator driven valve 22 to spout 12. Inthe illustrated embodiment, controller 24 is configured to open andclose valve 22 to turn on and off the fluid flow between valve bodyassembly 20 and spout 12. In another embodiment, controller 24 isfurther configured to proportionally control valve 22 to adjust the flowrate of the fluid flowing to spout 12. In an illustrative embodiment,actuator driven valve 22 is an electrically operable valve, such as asolenoid valve, and more particularly a magnetically latchingpilot-controlled solenoid valve, for example.

As illustrated in FIG. 1, controller 24 is coupled to and powered by apower supply 21. In one embodiment, power supply 21 is a building powersupply and/or a battery power supply. Controller 24 includes softwarestored in a memory and containing instructions for controlling valve 22.

In an alternative embodiment, hot water source 16 and cold water source18 are connected directly to actuator driven valve 22 to provide a fullyautomatic faucet without any manual controls. In yet another embodiment,controller 24 further controls an electronic proportioning or mixingvalve (not shown) coupled to the hot and cold water sources 16, 18 tosupply fluid to spout 12 from hot and cold water sources 16, 18. Similarto valve body assembly 20, the electronic proportioning valve, coupledbetween valve 22 and the hot and cold water sources 16, 18, is adjustedto control the mixture of hot and cold water and thus the temperature ofthe water flowing through spout 12. Faucet system 10 may further includea temperature sensor in fluid communication with the output of theproportioning valve to provide feedback to controller 24 for use incontrolling the water temperature.

Because actuator driven valve 22 is controlled electronically bycontroller 24, the flow of water can be controlled using an output froma sensor, such as a proximity sensor and/or a touch sensor, for example.In the illustrated embodiment, a capacitive sensor 26 is incommunication with controller 24 for providing signals to controller 24indicating the detection of an object (e.g. a user's hands) near or onspout 12. Other suitable sensors may be provided for detecting an objectnear faucet 10. As illustrated, an electrode 25 of capacitive sensor 26is coupled to spout 12, and an output from capacitive sensor 26 iscoupled to controller 24. Electrode 25 may be positioned in othersuitable areas of faucet system 10 for detecting the presence of auser's hands. In the illustrative embodiment, capacitive sensor 26 andelectrode 25 are used for both touch and hands free operation. In thehands free mode of operation, capacitive sensor 26 and controller 24detect a user's hands or other object within a detection area 27 locatednear spout 12. In one embodiment, detection area 27 includes the waterstream and the area immediately surrounding the water stream. Detectionarea 27 may be expanded to other areas depending on the location andsensitivity of capacitive sensor 26. In the touch mode of operation,capacitive sensor 26 and controller 24 detect a user's hands or otherobject upon contact with a surface of spout 12. Capacitive sensor 26 mayalternatively operate solely as a touch sensor or a proximity sensor. Anexemplary capacitive sensor 26 is a CapSense capacitive sensor availablefrom Cypress Semiconductor Corporation, although other suitablecapacitive sensors may be used.

In the illustrative embodiment of FIG. 1, with actuator driven valve 22opened, faucet system 10 is operated in a conventional manner, i.e., ina manual control mode through operation of handle(s) 14 and the manualvalve member(s) of valve body assembly 20. Conversely, with actuatordriven valve 22 closed and the manually-controlled valve body assembly20 set to select a water temperature and flow rate, the fluid flow isblocked with valve 22. To turn on the faucet assembly 10, actuatordriven valve 22 is activated by controller 24 when a proximity sensor,such as capacitive sensor 26, detects an object (such as a user's hands)within detection zone or area 27 to thereby toggle water flow on andoff. Alternatively or additionally, actuator driven valve 22 may betouch controlled using a touch sensor, such as capacitive sensor 26, totoggle water flow on and off. Further manual adjustment of the watertemperature and flow rate may be provided after opening the actuatordriven valve 22 by manipulating handle 14.

In one embodiment, controller 24 converts the output of capacitivesensor 26 into a count value. In the illustrated embodiment, anincreased capacitance detected with sensor 26 results in an increasedcount value, and a decreased capacitance detected with sensor 26 resultsin a decreased count value. See, for example, sensor output signal 302illustrated in FIG. 4 and described herein.

As described herein, the output signal from capacitive sensor 26 isillustratively used to control actuator driven valve 22 which therebycontrols the flow of water to the spout 12 from the hot and cold watersources 16 and 18. By sensing capacitance changes with capacitive sensor26, controller 24 is configured to make logical decisions to controldifferent modes of operation of system 10 such as changing between amanual mode of operation and a hands free mode of operation as describedin U.S. Pat. No. 7,537,023; U.S. application Ser. No. 11/641,574; U.S.Pat. No. 7,150,293; U.S. application Ser. No. 11/325,128; and PCTInternational Application Serial Nos. PCT/US2008/01288 andPCT/US2008/013598, the disclosures of which are all expresslyincorporated herein by reference.

The amount of fluid flowing from hot water source 16 and cold watersource 18 is determined based on one or more user inputs, such asdesired fluid temperature, desired fluid flow rate, desired fluidvolume, various task based inputs, various recognized presentments,and/or combinations thereof. As described herein, the control of fluidmay be provided manually with manual valve handle 14 or electronicallywith controller 24. As discussed herein, the system 10 may include anelectronically controlled mixing valve that is in fluid communicationwith both hot water source 16 and cold water source 18 and is controlledwith controller 24. Exemplary electronically controlled mixing valvesare described in U.S. Pat. No. 7,458,520 and PCT InternationalApplication Serial No. PCT/US2007/060512, the disclosures of which areexpressly incorporated by reference herein. In one embodiment, bothmanual valve handle 14 and controller 24 may be configured to controlthe mixing valve. Exemplary user inputs for controlling fluid flowinclude the position of manual valve handle 14, sensor feedback (e.g.temperature, flow rate, flow volume, etc.), and other suitable inputs.

In an illustrative embodiment, an operator of the electronic faucet 10can selectively enable or disable the proximity detector (e.g.capacitive sensor 26) using a mode selector switch 28 coupled tocontroller 24. Upon disabling the proximity detector, the hands freeand/or touch mode of faucet assembly 10 is disabled, and actuator drivenvalve 22 is opened to allow full control with manual handle 14. Anexemplary mode selector switch 28 includes a pushbutton, a toggleswitch, or another suitable user input. In one embodiment, faucet 10includes an indicator 29 controlled by controller 24 to provide a visualor audio indication when the electronic faucet 10 is in the hands freeand/or touch mode. An exemplary indicator 29 includes an LED or otherlight source or audible device positioned near faucet assembly 10.

In one embodiment, the hands free/touch mode is also configured to beenabled or disabled using a series of touches of spout 12 and/or handle14. In the illustrated embodiment, spout 12 is coupled to a faucet bodyhub 13 through an insulator 15. In one embodiment, faucet body hub 13 iselectrically coupled to manual valve handle 14. Therefore, insulator 15electrically isolates spout 12 from faucet body hub 13 and handle 14. Inthis illustrated embodiment, electrode 25 is directly coupled to spout12 and capacitively coupled to handle 14 so that capacitive sensor 26and controller 24 may determine whether the spout 12 or manual valvehandle 14 is touched by a user based on the difference in thecapacitance level of sensor 26 as illustrated, for example, in PCTInternational Publication No. WO2008/088534, the disclosure of which isincorporated herein by reference. As such, controller 24 may beprogrammed to disable or enable the hands free and touch mode, or toswitch between the hands free mode and the touch mode, based on thenumber, duration, and/or location of touches applied to spout 12 andhandle 14.

An illustrative embodiment of the hands free/touch mode of operation ismethod 200 illustrated in FIGS. 2-3C. FIG. 2 illustrates the majorcomponents or sub-routines of the method 200, including functionalblocks 210, 250, 260, 270, and 280. FIGS. 3A-3C illustrate the steps ofeach sub-routine of FIG. 2. Reference is made to faucet assembly 10 ofFIG. 1 throughout the description of FIGS. 2-3C. As described herein,method 200 illustratively adapts operation of faucet assembly 10 byautomatically adjusting appropriate on/off thresholds of valve 22 toaccount for variations in environmental factors. Method 200 furtherpermits continuous water flow as long as an object is detected withindetection area 27, such as in the water stream, of faucet assembly 10.

With further reference to FIGS. 2 and 3A, the illustrative method 200begins at the Get and Process Data functional block 210 where controller24 illustratively executes an algorithm provided in software stored inthe memory of controller 24. As described herein, in the Get and ProcessData functional block 210 controller 24 determines the stability of thesignal from capacitance sensor 26 and detects the presence of an object(i.e., the user's hands) in the detection area 27 (FIG. 1) or waterstream.

At Block 212 of FIG. 3A, controller 24 grabs new data, i.e., a newmeasurement/sample, from capacitance sensor 26. In the illustratedembodiment, the data acquired from sensor 26 at Block 212 is a countvalue that is proportional to the detected capacitance, as describedherein. The new data from sensor 26 is averaged with previously acquireddata from sensor 26 to generate a rolling average of data from sensor 26(AvgData). In one embodiment, the previously acquired data is theimmediately preceding measurement/sample from sensor 26. Alternatively,the previously acquired data may be several precedingmeasurements/samples from sensor 26. The new data from sensor 26 and thecurrent rolling average AvgData is stored in the memory of controller24. At Block 214, controller 24 subtracts the previously calculatedaverage data (PrevAvgData) from the new average data (AvgData).PrevAvgData is illustratively the calculated rolling average from theprevious execution of method 200. For example, PrevAvgData is theaverage of the previous two or more samples acquired from sensor 26prior to acquiring the new data from sensor 26 at Block 212. Thecalculated difference (SignalChange) at Block 214 is a measure of howmuch the signal from sensor 26, illustratively the measured capacitance,has changed from one sample to another.

If the change or variation of the signal from sensor 26 falls within apredetermined “noise” range or threshold, a Stability Counter isincremented by controller 24. The Stability Counter counts the number ofconsecutive instances that the difference between the previous tworolling average measurements (PrevAvgData and AvgData) falls within thepredefined noise threshold or range. If the Stability Counter reaches apredetermined value during the execution of method 200, controller 24determines that the signal from sensor 26 is “stable.” A “stable” signalfrom sensor 26 illustratively indicates that little or no motion of auser's hands or other object has been detected by sensor 26.

Referring to FIG. 3A, at decision Block 216 the controller 24 determinesif the calculated signal change (SignalChange) is less than a signalnoise limit (NoiseMaxThreshold). Signal noise is generated, for example,by the motion of a user's hands in proximity to capacitive sensor 26(for example, in detection area 27 or the water stream of the faucet).In one illustrative embodiment, the noise limit is predefined as a 20percent change in the signal value from sensor 26, although othersuitable percent changes could be used to define the noise limit. If thesignal change (SignalChange) is less than the noise limit(NoiseMaxThreshold), controller 24 determines at Block 218 if theStability Counter is greater than a predetermined value (StabilityValue). In the illustrated embodiment, the Stability Value is apredetermined counter value equal to the number of SignalChangecalculations that are performed by controller 24 in about one second ofelapsed time. In other words, the Stability Value is illustrativelyequal to the number of iterations of method 200 that are performed inabout one second. As such, when the Stability Counter exceeds theStability Value (i.e., when the signal change is less than the noiselimit for about one second), the signal from sensor 26 is determined tobe stable, thereby indicating that minimal or no motion is detected indetection zone 27. Other suitable values for the Stability Value may beused. For example, the Stability Value may correspond to the number ofiterations of method 200 that are performed in about three seconds, fiveseconds, ten seconds, or other suitable periods for determining that thecapacitive signal is stable. As described herein, a determination bycontroller 24 of a “stable” signal from sensor 26 is configured to closevalve 22 under some operating conditions.

If the Stability Counter is not greater than the Stability Value atBlock 218, the process continues to Block 220, where the StabilityCounter is incremented by 1. If the Stability Counter is greater thanthe Stability Value at Block 218, then the Stability Counter is reset tozero and a Signal Stability Flag is set to Stable at Block 222. In otherwords, when the Stability Counter exceeds the predetermined StabilityValue, the signal from sensor 26 is determined to be “stable” at Block222. By resetting the Stability Counter to zero at block 222, controller24 is illustratively configured to periodically reset the SignalStability Flag whenever the Stability Counter again exceeds theStability Value, thereby continuously monitoring the stability of thesignal.

If the calculated signal change (SignalChange) exceeds the noise limit(NoiseMaxThreshold) at Block 216, the signal from sensor 26 isdetermined to be noisy at Block 224, i.e., motion is detected indetection zone 27. Controller 24 sets the Signal Stability Flag to“Noisy” at Block 224. In addition, the Stability Counter is reset tozero to restart the signal stability determination, and a Noisy Counteris incremented by 1. The Noisy Counter illustratively counts the numberof consecutive instances that the signal change (SignalChange) betweenthe previous two rolling average measurements (PrevAvgData and AvgData)falls outside the predefined noise threshold (NoiseMaxThreshold). In oneembodiment, controller 24 monitors the duration that the signal fromsensor 26 is identified as “noisy” based on the Noisy Counter.

In addition to determining the stability of the signal from sensor 26,controller 24 also detects the presence of an object in detection zone27 by comparing the capacitance level from sensor 26 to thresholdvalues. When the detected capacitance level reaches or crosses athreshold level, an object is determined to be present in detection zone27. Referring to FIG. 3A, if valve 22 is currently closed at Block 226to block fluid flow, controller 24 compares the averaged data (AvgData)obtained at Block 212 to an open or “on” threshold value(OpenThreshold), as illustrated at Block 228. If the averaged data(AvgData) is greater than the open threshold value (OpenThreshold),controller 24 sets the Object Present Flag to “true” to indicate that anobject is detected in detection zone 27. If the averaged data (AvgData)is less than or equal to the open threshold value (OpenThreshold), theObject Present Flag is set to “false” to indicate that an object is notdetected in detection zone 27. As such, when the capacitance leveldetected with sensor 26 exceeds the predetermined threshold(OpenThreshold) and valve 22 is closed, controller 24 determines that anobject, such as a user's hand, is in detection zone 27.

Similarly, if valve 22 is currently open at Block 230, controller 24compares the averaged data (AvgData) from sensor 26 to a close or “off”threshold value (CloseThreshold), as illustrated at Block 232. If theaveraged data (AvgData) is less than the close threshold value(CloseThreshold) at Block 232, the Object Present Flag is set to “false”at Block 236 to indicate that an object is not detected in detectionzone 27. If the averaged data (AvgData) is greater than or equal to theclose threshold value (CloseThreshold) at Block 232, the Object PresentFlag is set to “true” at Block 240 to indicate that an object isdetected in detection zone 27. As such, once valve 22 is open,controller 24 sets a flag (Object Present Flag) indicating that anobject, such as a user's hand, is in detection zone 27 when thecapacitance level detected with sensor 26 exceeds the predeterminedthreshold (CloseThreshold). In the illustrated embodiment, the open andclose thresholds at Blocks 228 and 232 are predetermined count values.

In the illustrative embodiment of FIGS. 3A and 4, an object isconsidered to be present in detection zone 27 if the magnitude of thesignal from sensor 26 (e.g., signal 302 of FIG. 4) is greater than theopen or “on” threshold (OpenThreshold of FIG. 3A, line 304 of FIG. 4)when valve 22 is closed or when the magnitude of the signal is greaterthan the close or “off” threshold (CloseThreshold of FIG. 3A, line 306of FIG. 4) when valve 22 is open. In the illustrated embodiment, thethreshold value to keep valve 22 open (CloseThreshold) is greater thanthe threshold value to open valve 22 when valve 22 is closed(OpenThreshold). As described herein, the stability of the signal fromsensor 26, in addition to the CloseThreshold, is further considered indetermining when to close valve 22.

The CloseThreshold and OpenThreshold are illustratively count valuesthat correspond to capacitance levels detected with sensor 26. Asdescribed herein, the CloseThreshold and OpenThreshold areillustratively determined based on the steady state capacitance signalprovided with sensor 26. For example, the CloseThreshold andOpenThreshold are adjusted continuously or periodically based on thedetected capacitance level when valve 22 is closed and when thecapacitance signal is determined to be “stable,” as described herein. Inone exemplary embodiment, the CloseThreshold is about 100 counts greaterin value than the OpenThreshold, although other suitable differences maybe provided between CloseThreshold and OpenThreshold. An exemplaryOpenThreshold is about 350 counts, and an exemplary CloseThreshold isabout 450 counts. In one embodiment, the OpenThreshold is set to differfrom the steady state capacitance signal by a predetermined count value.For example, the OpenThreshold may be set to 50 counts greater than thecapacitance level detected with sensor 26 when faucet 10 is in a steadystate condition. Alternatively, the OpenThreshold may be set to deviatefrom the steady state capacitance signal by a predetermined percentage,and the CloseThreshold may be set to deviate from the OpenThreshold by apredetermined percentage.

In one embodiment, the OpenThreshold includes a first predeterminedrange of values, and the CloseThreshold includes a second predeterminedrange of values. As such, controller 24 compares a measure of the signalprovided with sensor 26 with each range of values to determine if anobject is detected in detection area 27 and to determine when toopen/close valve 22. For example, at block 228, if the averaged data(AvgData) falls outside the first predetermined range, controller 24sets the Object Present Flag to “true” at block 234. If the averageddata (AvgData) falls within the first predetermined range, the ObjectPresent Flag is set to “false” at block 238. Similarly, at block 232, ifthe averaged data (AvgData) falls outside a second predetermined range,controller 24 sets the Object Present Flag to “true” at block 240. Ifthe averaged data (AvgData) falls within the second predetermined range,the Object Present Flag is set to “false” at block 236. In oneembodiment, the second predetermined range of values of theCloseThreshold is greater than the first predetermined range of valuesof the OpenThreshold. Further, the first and second predetermined rangesillustratively include count values representative of a measure ofcapacitance. For example, the first predetermined range of theOpenThreshold includes count values between zero and a first thresholdcount value, the second predetermined range of the CloseThresholdincludes count values between zero and a second threshold count value,and the second threshold count value is greater than the first thresholdcount value. In one embodiment, the second threshold count value isabout 100 counts greater than the first threshold count value. Othersuitable predetermined ranges and other differences between the firstand second threshold count values may be provided.

With reference to FIGS. 2 and 3B, the illustrative method 200 continuesat the Criteria to Change Threshold functional block 250. As describedherein, controller 24 is configured to modify the on/off thresholds(OpenThreshold and CloseThreshold) of valve 22 if the signal from sensor26 is stable and valve 22 is closed, i.e., when faucet 10 is in a steadystate condition. In one embodiment, controller 24 modifies the on/offthresholds due to a change in the environmental conditions of faucet 10,such as a buildup of soap scum on faucet 10 or the presence of a soapdish or other objects near faucet 10, for example, that affect thecapacitance level detected with sensor 26. For example, a buildup ofsoap on the faucet 10 or the presence of a soap dish near faucet 10 maycause the capacitance level detected with sensor 26 to increase ordecrease regardless of the presence of a user's hands in detection zone27. As such, a stable signal from sensor 26 may have an increased ordecreased magnitude due to the environmental changes of faucet 10. Inthe illustrated embodiment, controller 24 is configured to adjust theon/off thresholds based on the detected steady state signal from sensor26 and at least one predefined offset, as described herein.

Referring to Block 252 of FIG. 3B, if the signal from sensor 26 isdetermined to be stable (based on the Signal Stability Flag) and valve22 is closed, controller 24 determines that faucet 10 is in a steadystate condition and proceeds to blocks 254, 256, and 258 to modify theon/off thresholds. Controller 24 may alternatively be configured tomodify the on/off thresholds under other conditions, such as when valve22 is open, for example. As described herein, the on/off thresholds aremodified by adding an offset to each threshold. In one embodiment, theoffset(s) are predetermined and stored in the memory of controller 24.In another embodiment, the offset(s) are adjusted automatically withcontroller 24 or manually based on the environmental conditions offaucet 10.

At Block 254, controller 24 acquires new data, i.e., a new capacitancemeasurement/sample, from capacitance sensor 26. In the illustratedembodiment, the new data acquired at Block 254 is the same new dataacquired at Block 212 of FIG. 3A, although additional new data may beacquired. As with Block 212, the new data from sensor 26 is averagedwith previously acquired data from sensor 26 to generate a rollingaverage of data from sensor 26 (AvgData) at Block 254. The previouslyacquired data includes one or more immediately precedingmeasurement/samples from sensor 26. In the illustrated embodiment, therolling average AvgData calculated at Block 254 is the same rollingaverage AvgData calculated at Block 212.

At Blocks 256 and 258, the on/off thresholds for valve 22 are modified.At Block 256, the open or “on” threshold OpenThreshold is set to the sumof the calculated rolling average (AvgData) and a first predeterminedoffset (First Offset). At Block 258, the close or “off” threshold is setto sum of the modified OpenThreshold and a second predetermined offset(Second Offset). As such, the First Offset represents the differencebetween the detected average capacitance level (AvgData) and theOpenThreshold, and the Second Offset represents the difference betweenthe OpenThreshold and the CloseThreshold. In one embodiment, the offsetvalves (First Offset and Second Offset) are determined during periodicsystem calibrations and are stored in the memory accessible bycontroller 24. In one exemplary embodiment, the Second Offset is equalto about 100 counts, as described herein, although other values of theSecond Offset may be provided for setting the difference betweenCloseThreshold and OpenThreshold. In the illustrated embodiment, theSecond Offset is greater than the First Offset, although the SecondOffset may alternatively be less than or equal to the First Offset.Exemplary values of First Offset are 20 counts, 50 counts, or 75 counts,although other suitable values may be provided for the First Offset.

Following the Criteria to Change Thresholds functional block 250, method200 proceeds to the Criteria to Turn On the Valve functional block 260to set a flag for turning on or opening valve 22 when an object isdetected in detection zone 27. Referring to Block 262 of FIG. 3B,controller 24 determines if an object is present based on the ObjectPresent Flag set at functional block 210 of FIG. 3A, i.e., based uponAvgData being greater than the OpenThreshold at Block 228 or theCloseThreshold at Block 232. If an object is present based on the ObjectPresent Flag and valve 22 is currently closed, controller 24 sets anOpenFlag to “true” at Block 264 of FIG. 3C.

If an object is determined to be not present based on the Object PresentFlag or if valve 22 is currently open at Block 262, controller 24proceeds to the Criteria to Turn Off the Valve functional block 270 ofFIG. 3C to determine whether to close valve 22. At functional block 270,controller 24 is configured to set a flag to close valve 22 if the valve22 is open, the signal from sensor 26 is stable, and an object is notdetected in detection zone 27. As such, if valve 22 is open and thesignal from sensor 26 is determined to be “noisy,” controller 24illustratively does not close valve 22 even if an object is not detectedin detection zone 27. In particular, if valve 22 is open and the signalfrom sensor 26 is stable (based on the Signal Stability Flag) at Block272, controller 24 determines if an object is present based on theObject Present Flag set at functional block 210. If an object isdetermined to not be present in detection zone 27 based on the ObjectPresent Flag (i.e., based upon AvgData being less than theCloseThreshold at Block 232 or the OpenThreshold at Block 228), and ifthe signal from sensor 26 is “stable” and valve 22 is open, controller24 sets a CloseFlag to “true” at Block 274 of FIG. 3C.

Following functional blocks 260 and 270 of FIG. 3C, method 200 continuesto the Valve Handler functional block 280 illustrated in FIGS. 2 and 3Cto either open or close valve 22. More particularly, controller 24 opensvalve 22 at Block 282 upon the OpenFlag being set to “true” at Block264. Similarly, controller 24 closes valve 22 at Block 282 upon theCloseFlag being set to “true” at Block 274.

FIG. 4 illustrates a representative capacitive sensing signal 302received by controller 24 from capacitive sensor 26. The signal 302 isplotted such that time (illustratively in seconds) is represented in thehorizontal direction (X axis) and the sensor output (illustratively incounts) is represented in the vertical direction (Y axis). The open or“on” threshold (OpenThreshold) is represented by line 304, and the closeor “off” threshold (CloseThreshold) is represented by line 306. Asillustrated, close threshold 306 is positioned above the open threshold304, indicating that valve 22 is configured to close at a greatermagnitude of signal 302 than the magnitude of signal 302 required toopen valve 22. As such, the close threshold 306 requires the user to becloser, and in some cases touching, faucet 10 in order for signal 302 tostay above the close threshold 306. As described herein, the open andclose thresholds 304, 306 are dynamically changed by controller 24 basedon the environmental conditions of faucet 10.

Referring to FIG. 4, capacitance signal 302 is below the open threshold304 between times t₀ and t₁, indicating that an object is not detectedin detection zone 27. As such, valve 22 of faucet 10 is closed. At timet₁, signal 302 exceeds the open threshold 304, indicating that an objectis detected in detection zone. As such, valve 22 is opened at time t₁ tosupply water to spout 12. Between times t₂ and t₃, controller 24determines that the signal is “noisy” based on functional block 210 ofthe method 200 described herein. Since signal 302 is above the openthreshold 304 and noisy, valve 22 remains open despite signal 302 beingbelow the close threshold 306. At time t₃, signal 302 exceeds the closethreshold 306, and thus valve 22 remains open regardless of whethersignal 302 is noisy or stable. For example, signal 302 may exceed theclose threshold 306 when the user touches spout 12. Between times t₃ andt₄, signal 302 is again above the open threshold 304 but below the closethreshold 306. Valve 22 remains open between times t₃ and t₄ becausecontroller 24 determines the signal 302 to be noisy. Beginning at timet₄, signal 302 remains below the close threshold 306, but controller 24determines signal 302 to be stable. As such, controller 24 closes valve22 at time t₄ to block water from flowing through spout 12 due to signal302 being both stable and less than the close threshold 306.

U.S. patent application Ser. No. 12/525,324, filed Nov. 11, 2009; U.S.patent application Ser. No. 12/600,769, filed Nov. 18, 2009; and U.S.patent application Ser. No. 12/763,690, filed Apr. 20, 2010, areexpressly incorporated by reference herein.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe spirit and scope of the invention as described and defined in thefollowing claims.

The invention claimed is:
 1. A method of controlling an electronicfaucet, the method comprising the steps of: providing a faucet includinga spout having a passageway configured to deliver fluid through thespout, a valve positioned in the passageway, and a capacitive sensorcoupled to the faucet; detecting a capacitive signal provided with thecapacitive sensor; comparing a measure of the capacitive signal with athreshold; opening the valve when the measure of the capacitive signalreaches the threshold; and adjusting the threshold in response to atleast one environmental factor.
 2. The method of claim 1, wherein theadjusting step is based on the measure of the capacitive signal and anoffset value.
 3. The method of claim 1, wherein the valve is opened whenthe measure of the capacitive signal is greater than the threshold. 4.The method of claim 1, wherein the comparing step includes comparing themeasure of the capacitive signal with a first threshold and a secondthreshold, and wherein the opening step includes opening the valve whenthe measure of the capacitive signal exceeds the first threshold.
 5. Themethod of claim 4, wherein the second threshold is greater than thefirst threshold, and further including the step of maintaining the valvein an open position when the measure of the capacitive signal exceedsthe second threshold.
 6. The method of claim 5, further including thestep of maintaining the valve in an open position when the measure ofthe capacitive signal exceeds the first threshold and a noise level ofthe capacitive signal exceeds a threshold noise level.
 7. The method ofclaim 1, further including the step of detecting the at least oneenvironmental factor based on the measure of the capacitive signal. 8.An electronic faucet comprising: a spout having a passageway configuredto deliver fluid through the spout; an electrically operable valvepositioned in the passageway; a capacitive sensor coupled to the faucet;and a controller in electrical communication with the capacitive sensorand defining a threshold, the capacitive sensor being configured to senda capacitive signal to the controller, the controller being configuredto open the valve when a measure of the capacitive signal reaches thethreshold and to adjust the threshold in response to at least oneenvironmental factor.
 9. The faucet of claim 8, wherein the controllerdefines a first threshold and a second threshold greater than the firstthreshold, and the controller is configured to open the valve when themeasure of the capacitive signal exceeds the first threshold.
 10. Thefaucet of claim 9, wherein the controller is configured to maintain thevalve in an open position when the measure of the capacitive signalexceeds the second threshold.
 11. The faucet of claim 9, wherein thecontroller is configured to maintain the valve in an open position whenthe measure of the capacitive signal is between the first threshold andthe second threshold and when a noise level of the capacitive signalexceeds a threshold noise level.
 12. The faucet of claim 9, wherein thecontroller is configured to adjust at least one of the first thresholdand the second threshold in response to the at least one environmentalfactor, the adjusted second threshold being based on the adjusted firstthreshold.
 13. The faucet of claim 8, wherein the controller isconfigured to adjust the threshold upon at least one of the valve beingclosed and the capacitive signal being stable.
 14. The faucet of claim13, wherein the controller determines the capacitive signal is stablewhen a detected variation of the capacitive signal is within apredetermined range.
 15. The faucet of claim 8, further including amanually operable valve positioned in the passageway and a handlecoupled to the manually operable valve and configured to control themanually operable valve, wherein the manually operable valve isconfigured to control at least one of the temperature and flow rate ofthe fluid delivered through the spout.
 16. The faucet of claim 8,wherein the at least one environmental factor is detected based on themeasure of the capacitive signal.
 17. The faucet of claim 16, whereinthe at least one environmental factor is detected based on the measureof the capacitive signal being at a steady state and having a magnitudethat is outside a threshold range.
 18. The faucet of claim 16, whereinthe measure of the capacitive signal is indicative of at least one of aconductive item and a soap deposit being positioned in proximity to thefaucet.
 19. The faucet of claim 8, wherein the controller adjusts thethreshold based on the measure of the capacitive signal and an offsetvalue.
 20. The faucet of claim 8, wherein the capacitive sensor includesan electrode coupled to the spout.